Q. We have a spare bedroom that is home to a college-age young man who isn't home much, and now doubles as our guest room. I'd like to decorate it so that it works for both. Any ideas?

Don't be too sure that your college boy won't move back in when school is finished. It seems to be a trend. But there is plenty of scope for designing a wonderfully welcoming bedroom that will receive accolades from your son and guests.

One timeless combination that I'd suggest is stripes and plaids. Both these patterns take on very different moods depending on their color mix. This bedroom is sophisticated and comfortable with its smoky gray tones and soft white bedding. The striated wallpaper adds texture and focus to the wall behind the bed. There are many wallpaper patterns that incorporate stripes. Variable widths in multiple colors would be young and fun for a child's room; fat stripes are modern and dramatic.

Although the walls are on the dark side, the maple hardwood floor and light round bedside tables are fresh and modern, and keep the room from feeling too heavy. The simple pattern of stripes and squares repeats in the bed pillows and blanket.

Using a basic grounding palette on the walls gives you the freedom to experiment with your accessories – it's easy to adjust the ambience with a shot of color in the blanket and pillows, picture frames and carpet. Personal collections and memorabilia should be kept to a minimum and can be stored away until your son returns. Leave space on the night stands and in the closet for guests to unpack their gear. It is a thoughtful touch to place an item or two in your guest room that connects directly to the visitor. A framed picture of you all together, a favorite bouquet of flowers or bath soap, or a bedtime snack will let your company know that they are welcome.

Mosaic tile

Q. I read your column on mosaic tile and want to tile a bathroom countertop, which is a horrible shade of orange Formica. Will this work?

Yes, this is a great solution for transforming your countertop. The key is preparation. Formica and laminates are solid, slippery surfaces that won't hold on to paint or tile glue. Wash the counter with a strong detergent such as TSP to dull the surface, and a bit of sanding wouldn't hurt either. Then apply a high-adhesion primer that is designed to cover slippery surfaces, which include high-gloss paint, oil paint and laminates. Let dry overnight, and then you are ready to apply your mosaic design. Remember to seal the grout.